Opinions Wanted: Buy or Trade-In 2011 X5

[AustexX5]

I have a 2011 X5 3.5 Premium with Sport Package and NAV that I did the Owner's Choice program back in November 2010. I am getting close to the end of the program contract date. I went through that program to take advantage of some tax incentives. Sticker on the X5 was about $65k and my monthly payments (not counting tax incentives) is $1,055/mo. The X5 will have approximately 45k miles on it by the end of the contract, but is still in mint condition. My options are to:

1. Turn it in and pay a $250 disposition fee and walk away
2. Trade it in on a new BMW or any other car and enjoy the sales tax savings of whatever the market value is. If the market value is less than the $35k residual, might not make sense.
3. Buy it for the residual of $35k

I am not 100% in love with the new 2014 X5s so I am at a bit of crossroad at what to do. I think that if the market value is more than the residual, then I'll keep it but I wanted to get some different perspectives.